Inventory control system and method

ABSTRACT

An inventory control system and method uses a locating device associated with a mover and identifies an ID tagged asset using an ID reader also associated with the mover. Thus, a single relatively high-cost locating device may be temporarily associated with the asset, enabling precise location of a multitude of assets as a mover traverses an inventory area. The asset location and identification may be associated in a database. The asset location may be refined by using additional measurement devices, for example a forklift height sensor, to determine extension from a locating device. A further embodiment utilizes RFID or barcode technology for the ID tag. The locating device may utilize near-field location technology, signals-of-opportunity, or other RTLS technologies.

RELATED APPLICATIONS

The present application is a continuation-in-part of U.S. patentapplication Ser. No. 11/890,350 titled: “Asset localizationidentification and movement system and method,” filed Aug. 6, 2007, nowU.S. Pat. No. 7,957,833 issued Jun. 7, 2011 and its antecedents. Thepresent application is a continuation-in-part of U.S. patent applicationSer. No. 12/977,067 titled: “Near-field electromagnetic location systemand method,” filed Dec. 23, 2010 and its antecedents. The presentapplication is a continuation in part of U.S. patent application Ser.No. 12/796,643 titled: “Method and apparatus for determining locationusing signals-of-opportunity” filed Jun. 8, 2010. The presentapplication is a continuation in part of U.S. patent application Ser.No. 12/843,002 titled: “Malicious attack response system and method,”filed Jul. 23, 2010. The present application is a continuation in partof U.S. patent application Ser. No. 12/391,209 titled: “Multiple phasestate near-field electromagnetic system and method for communication andlocation,” filed Feb. 23, 2009 and its antecedents. The presentapplication is a continuation in part of U.S. patent application Ser.No. 12/834,821 titled: “Space efficient magnetic antenna method,” filedJul. 12, 2010 and its antecedents. The present application is acontinuation in part of U.S. patent application Ser. No. 12/857,528titled: “Planar antenna system,” filed Aug. 16, 2010 and itsantecedents. The present application is a continuation in part of U.S.provisional patent application 61/470,735 titled: “Directiveelectrically small antenna system and method,” filed Apr. 1, 2011. Allof the above listed US patent and patent applications and theirantecedents are hereby incorporated herein by reference in theirentirety.

GOVERNMENT LICENSE RIGHTS

The U.S. Government has a paid up license in this invention and theright in limited circumstances to require the patent owner to licenseothers on reasonable terms as provided for by the terms of contractOII-0646339 awarded by National Science Foundation.

BACKGROUND

1. Field of the Invention

The present invention relates generally to systems and methods forautomated asset and personnel locating.

2. Background of the Invention

Within a warehouse or logistics system, there is an ongoing need toprovide a continuously updated inventory and to know the location ofeach asset. Proposed methods use a mix of technology in the form of barcodes and the like with software manually updated for locationinformation. Automated location information typically includes activedevices that can be too expensive for all but the most valuable assets.

RFID tags and barcodes have been proposed for inventory control in awarehouse or logistics system, because of their low cost and ease ofuse, but they cannot be read at a distance, requiring physical proximityto read the tag and requiring a fork lift operator to exit the fork liftto operate the barcode reader and manually match the entry with thelocation. Location equipment can be relatively bulky and costly, toobulky and costly to be assigned one to one with every asset as someassets may be smaller than and cost less than the location equipment.One popular form of location equipment, GPS, lacks the precision tolocate an asset to a bin on a shelf and lacks coverage inside abuilding, particularly a building with a metal roof or other complexmetal structure. Location equipment that is not associated andidentified with a particular asset lacks a way to identify the assetbeing located without manual entry.

In view of the foregoing, there is a great need for a location andidentification system and method that can provide accurate locationinformation and asset identification at a reasonable cost.

BRIEF SUMMARY OF THE INVENTION

Briefly, the present invention pertains to an inventory control method.The method begins by identifying an asset by associating anidentification tag with the asset and reading the identification tag (orID tag) with an ID tag reader physically associated with a mover. Theidentification tag may be an RFID tag, or an optical barcode tag. Themover, which may be a forklift, person, robot, or other agent, isassociated with an RTLS tag. Then, the method logically associates theasset with the RTLS tag and determines location coordinates for themover. Finally, the method calls for logically disassociating the assetfrom the RTLS tag and recording location coordinates of the asset basedon the determined location coordinates for the mover. The locationcoordinates for the asset may be further refined by measured extensionfrom the location coordinates for the mover. The RTLS tag may be anactive RTLS tag or a passive RTLS tag. A passive RTLS tag may employsignals-of-opportunity in determining a location.

The invention also teaches an inventory control system comprising anRTLS tag associated with a mover (for determining location of themover), an ID tag reader associated with the mover (for determiningidentification of an asset from an ID tag associated with an asset), anda computer in communication with the RTLS tag and the ID tag reader forrecording a location of the asset. The computer is configured forassociating the location of the mover with the identification of theasset. The RTLS tag may be an active RTLS tag for transmitting alocation signal. In this embodiment, a set of locator receivers receivethe location signal and convey measurements of the receiving signal to acomputer. The computer determines location coordinates of the activeRTLS tag based on the measurements of the location signal. In a furtherembodiment, locator receivers determine location coordinates of theactive RTLS tag based on the measurements of the location signal, andconvey the coordinates to the computer.

The inventory control system may also employ a passive RTLS tag as theRTLS tag. The passive RTLS tag may employ signals-of-opportunity indetermining a location. Here again, the identification tag may be andRFID tag, or an optical barcode tag. Determining the locationcoordinates for the asset may utilize measured extension from thelocation coordinates for the mover, which may be a forklift, person,robot, or other agent. In an alternate embodiment, an inventory controlsystem comprises an active RTLS tag for transmitting a location signal,means for determining location coordinates for the active RTLS tag basedon the location signal, an ID tag reader in communication with acomputer, said ID tag reader for reading an asset identification from anID tag associated with an asset in an inventory area; and a mover forcarrying the ID tag reader and the active RTLS tag to a plurality oflocations within the inventory area. The location coordinates for theactive RTLS tag are determined by the means for determining the locationcoordinates while the active RTLS tag is in a known relative proximityto the asset. The inventory control system obtains an estimation oflocation coordinates for the asset from the location coordinates for theactive RTLS tag. The estimate may include the step of determininglocation coordinates for the asset by measured extension from thelocation coordinates for the mover, which may be a forklift, person,robot, or other agent. Finally, the inventory control system isconfigured for associating the location coordinates for the asset withthe asset identification.

These and further benefits and features of the present invention areherein described in detail with reference to exemplary embodiments inaccordance with the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is described with reference to the accompanyingdrawings. In the drawings, like reference numbers indicate identical orfunctionally similar elements.

FIG. 1 is an exemplary process flow diagram showing an assetidentification, localization, and movement process in accordance withthe present invention.

FIG. 2 is an exemplary schematic diagram describing one embodiment asystem for identification, localization, and movement of an asset.

FIG. 3 is a process flow diagram showing an illustrative logisticsprocess encompassing the asset identification, localization, andmovement process of FIG. 1.

FIG. 4 is a schematic diagram of an illustrative logistics facility.

FIG. 5 is an exemplary schematic diagram describing forklifts placingassets at various levels in a rack.

FIG. 6A is a schematic diagram showing a first exemplary embodimentasset and personnel localizing system involving a worker using an ID tagreader.

FIG. 6B is a schematic diagram showing a second exemplary embodimentasset and personnel localizing system involving a healthcare workerusing a localizing ID reader (LIDR) to identify and localize a varietyof assets.

FIG. 7 is a functional block diagram showing an exemplary near fieldlocator receiver for use in conjunction with an asset and personnellocation, identification, and movement system.

FIG. 8 is a mechanical diagram showing a side view of a locator receiverfor use in conjunction with an asset and personnel location,identification, and movement system.

FIG. 9 is a mechanical diagram showing a top view of a locator receiverfor use in conjunction with an asset and personnel location,identification, and movement system.

FIG. 10 is a functional block diagram showing an exemplary active RTLStag for use in conjunction with an asset and personnel location,identification, and movement system.

FIG. 11 is a functional block diagram showing an exemplary ID tag readerfor use in conjunction with an asset and personnel location,identification, and movement system.

FIG. 12 is a block diagram showing interfaces for an exemplary LIDR foruse in conjunction with an asset and personnel location, identification,and movement system.

FIG. 13 is a mechanical diagram showing an alternate embodiment activeRTLS tag for use in conjunction with an asset and personnel location,identification, and movement system.

FIG. 14 is a schematic diagram showing an inventory control system.

FIG. 15A is an exemplary process flow diagram showing an inventorycontrol method in accordance with the present invention.

FIG. 15B is an alternate exemplary process flow diagram showing aninventory control method in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Overview of theInvention

The present invention provides a system for automated positioning ofpotentially thousands of items in a logistics, manufacturing, healthcare, or other setting by combining the best features of assetidentification technology (for instance, radio frequency identification(RFID) barcode tags) with the capabilities of real-time location systems(RTLS) to provide a tow cost system for maintaining location awarenessof a multitude assets. This overview surveys both ID tags well-suitedfor use in an identification system or method, as well as a variety ofRTLS approaches.

Asset Identification Technology

A variety of asset identification tag technologies are known in the art,including Radio Frequency Identification (RFID), barcode, and opticalcharacter reading (OCR).

REID tags are typically low cost passive tags that can be excited by RFenergy, typically from within a meter or so and respond by transmittingan number and potentially other status information. Certain otherwise“passive” RFID tags employ a long life battery to increase the strengthof the radiated signal upon interrogation. Such tags should beconsidered subsumed under the term “passive tag,” “ID tag,” orequivalently, “identification tag.”

Barcode tags are typically optical and are read optically. Barcode tagsinclude the familiar Universal Product Code (UPC) barcodes of thesupermarket and also include numerous standards and formats includingtwo dimensional barcodes capable of high density information. 2Dbarcodes include “Aztec Code,” “Intercode,” “QR Codes,” Datamatrix, EZCode, and many others.

Numerous other similar asset identification tag technologies have beendeveloped and are continually being developed for the numerousapplications of these devices. In some cases, an asset identificationdevice (i.e. an “ID tag reader,” or an “interrogator”) will employmultiple discrete asset identification technologies to enable asuccessful identification. Within this disclosure, these devices arecollectively referred to as identification tags whether they are appliedas tags or stick on labels or built into the asset, or otherwiseassociated with the asset. Identification tags are typicallyadvantageous for their very low cost, low weight and small size.

Real Time Location System Technology

Real-time location system (RTLS) devices track an object's movement andmeasure the object's location to sufficient accuracy to identify theposition of the object within the correct bin or region in the storagearea or elsewhere. An important sub-set of RTLS use active wirelessdevices. Active RTLS may employ 2.4 GHz signals (for instance, Wi-Fi®,Bluetooth®, or ZigBee®), optical, IR, or laser signals, acousticsignals, ultra-wideband (UWB) signals, near-field signals, or otherwireless signals. Active RTLS methods may include time-of-flight,time-difference-of-arrival, Received Signal Strength Indicator (RSSI),multilateration, line-of-sight, direction finding, radar, RFfingerprinting, near-field electromagnetic ranging (NFER®) technology,or other methods. Depending on the context, any of these active RTLStechnologies may be suitable, however an emerging approach shows greatpromise.

Incumbent location providers take high frequency, short wavelengthwireless systems, like Wi-Fi or UWB, that were optimized for high datarate communications, and they try to use them to solve the challengingproblem of indoor wireless location. But location and communication aretwo fundamentally different problems requiring fundamentally differentsolutions, particularly in the most challenging RF propagationenvironments.

Applicants have pioneered a solution. NFER® technology offers a wirelessphysical layer optimized for real-time location in the most RF hostilesettings. NFER® systems exploit near-field behavior within about a halfwavelength of a tag transmitter to locate a tag to an accuracy of 1-3ft, at ranges of 60-200 ft, all at an infrastructure cost of $0.50/sqftor less for most installations. NFER® systems operate at lowfrequencies, typically around 1 MHz, and long wavelengths, typicallyaround 300 m. FCC Part 15 compliant, low-power, low frequency tagsprovide a relatively simple approach to wireless location that is simplybetter in difficult environments.

Low frequency signals penetrate better and diffract or bend around thehuman body and other obstructions. This physics gives NFER® systems longrange. There's more going on in the near field than in the far field.Radial field components provide the near field with an extra (third)polarization, and the electric and magnetic field components are notsynchronized as they are for far-field signals. Thus, the near fieldoffers more trackable parameters. Also, low-frequency, long-wavelengthsignals are resistant to multipath. This physics gives NFER.® systemshigh accuracy. Low frequency hardware is less expensive, and less of itis needed because of the long range. This makes NFER® systems moreeconomical in more difficult RF environments,

Near field electromagnetic ranging was first fully described inapplicant's “System and method for near-field electromagnetic ranging”(Ser. No. 10/355,612, filed Jan. 31, 2003, now U.S. Pat. No. 6,963,301,issued Nov. 8, 2005), This application is incorporated in entirety byreference. Some of the fundamental physics underlying near fieldelectromagnetic ranging was discovered by Hertz [Heinrich Hertz,Electric Waves, London: Macmillan and Company, 1893, p. 152]. Hertznoted that the electric and magnetic fields around a small antenna start90 degrees out of phase close to the antenna and converge to being inphase by about one-third to one-half of a wavelength. This is one of thefundamental relationships that enable near field electromagneticranging. A paper by one of the inventors [H. Schantz, “Near field phasebehavior,” 2005 IEEE Antennas and Propagation Society InternationalSymposium, Vol. 3A, 3-8 Jul. 2005, pp. 237-240] examines thesenear-field phase relations in further detail. Link laws obeyed bynear-field systems are the subject of another paper [H. Schantz, “Nearfield propagation law & novel fundamental limit to antenna gain versussize,” 2005 IEEE Antennas and Propagation Society InternationalSymposium, Vol. 3B, 3-8 Jul. 2005, pp. 134-137]. In addition to anactive RTLS tag (or fixed locator-mobile beacon) architecture, theteachings of U.S. Pat. No. 6,963,301 encompass a passive location tag(or fixed beacon-mobile locator) architecture. In this architecture, thepassive location tag (or passive RTLS tag) is a receiver that may beincorporated or associated with a vehicle or person to provide positioninformation from signals emitted by fixed transmit beacons. A beacon mybe an uncooperative source of electromagnetic radiation, like a signalfrom an AM broadcast station or other signal-of-opportunity. In thesense taught by Applicants, a “passive RTLS tag” is passive in the sensethat it does not emit signals in the process of obtaining location data,rather it receives and characterizes signals so as to determine locationof an associated mover. Determination of location may be performedeither locally (within the passive RTLS tag) or remotely (by conveyingsignal characterization data to a remote server for locationdetermination),.

Complicated propagation environments do tend to perturb the near-fieldphase relations upon which NFER® systems rely. Applicants have overcomethis problem using calibration methods described in “Near-fieldelectromagnetic positioning system and method” (Ser. No. 10/958,165,filed Oct. 4, 2004, now U.S. Pat. No. 7,298,314, issued Nov. 20, 2007).Additional calibration details are provided in applicant's “Near-fieldelectromagnetic positioning calibration system and method” (Ser. No.11/968,319, filed Nov. 19, 2007, now U.S. Pat. No. 7,592,949, issuedSep. 22, 2009). Still further details of this calibration are providedin applicant's co-pending “Near-field electromagnetic calibration systemand method” (Ser. No. 12/563,960 filed Sep. 21, 2009, now U.S. Pat. No.7,859,452, issued Dec. 28, 2010).

Applicant's unique algorithms enable innovative techniques fordisplaying the probability density and other aspects of locationinformation, as described in applicant's “Electromagnetic location anddisplay system and method,” (Ser. No. 11/500,660, filed Aug. 8, 2006,now U.S. Pat. No. 7,538,715, issued May 26, 2009).

Applicants discovered that orthogonal magnetic antennas offer uniqueadvantages for transmission and reception in real-time location systemsand elsewhere. Details may be found in “Near-field location system andmethod,” (Ser. No. 11/272,533, filed Nov. 10, 2005, now U.S. Pat. No.7,307,595, issued Dec. 11, 2007). Additional compact antenna designs areshown in applicant's “Space efficient magnetic antenna system,” (Ser.No. 11/473,595, filed Jun. 22, 2006, now U.S. Pat. No. 7,755,552 issuedJul. 13, 2010). Other antenna concepts of value in an RTLS and elsewhereare disclosed in Applicant's co-pending “Planar antenna system,” (Ser.No. 12/857,528, Aug. 16, 2010), and “Space efficient magnetic antennamethod,” (Ser. No. 12/834,821, filed Jul. 12, 2010). Applicant's“Directive electrically small antenna system and method,” (ProvisionalPatent Application 61/470,735 filed Apr. 1, 2011) presents furtherantennas of use in conjunction with an RTLS.

Further, the phase properties of near-field signals from orthogonalmagnetic and other multiple antenna near-field transmission signalsenable additional phase comparison states that can be used for locationand communication, as described in applicant's co-pending “Multi-statenear-field electromagnetic system and method for communication andlocation,” (Ser. No. 12/391,209, filed Feb. 23, 2009).

Near-field electromagnetic ranging is particularly well suited fortracking and communications systems in and around standard cargocontainers due to the outstanding propagation characteristics ofnear-field signals. This application of NFER® technology is described inapplicant's “Low frequency asset tag tracking system and method,” (Ser.No. 11/215,699, filed Aug. 30, 2005, now U.S. Pat. No. 7,414,571, issuedAug. 19, 2008).

Applicants have also discovered that near-field electromagnetic rangingworks well in the complicated propagation environments of nuclearfacilities and warehouses. An NFER® system provides the RTLS in apreferred embodiment of applicants' co-pending “System and method forsimulated dosimetry using a real-time location system” (Ser. No.11/897,100, filed Aug. 29, 2007). An NFER® system also provides thereal-time location system in a preferred embodiment of applicants'“Asset localization, identification, and movement system and method”(Ser. No. 11/890,350, filed Aug. 6, 2007, now U.S. Pat. No. 7,957,833issued Jun. 7, 2011).

In addition, applicants recently discovered that AM broadcast bandsignals are characterized by “near field” behavior, even manywavelengths away from the transmission tower. These localized near-fieldsignal characteristics provide the basis for a “Method and apparatus fordetermining location using signals-of-opportunity” (Ser. No. 12/796,643,filed Jun. 8, 2010). The techniques therein disclosed enable an RTLScomprising a mobile tag receiver employing signals-of-opportunity todetermine precise location or position. More generically, passivereceiver tag RTLS employing an uncooperative signal is described inApplicant's co-pending “Near-field electromagnetic location system andmethod,” (Ser. No. 12/977,067, filed Dec. 23, 2010) along with otherimprovements in the RTLS arts. Perhaps the best known passive receiverRTLS is the Global Positioning System (GPS). GPS would be suitable foruse as a passive RTLS tag in the present invention in an outdoor orother environment where GPS signals are available. Other examples ofpassive RTLS tags include those operating by receiving RF signals anddetermining location through RF fingerprinting, RSSI or other suitabletechniques.

Applicants also discovered that a path calibration approach can yieldsuccessful location solutions particularly in the context of firstresponder rescues, as detailed in applicant's “Firefighter location andrescue equipment” (Ser. No. 13/021,711, filed Feb. 4, 2011).

Applicant's “Malicious attack response system and method,” (Ser. No.12/843,002 filed Jul. 23, 2010) discusses innovative means of securing acomputer network, such as an inventory or management control system,from an attack outside the network.

All the above referenced US patents are incorporated herein by referencein their entirety.

Alternate technology RTLS tags may employ any of a variety of RTLStechnologies. One example is transponder RTLS in which the RTLS tag bothtransmits and receives signals as in a time-of-flight ranging ormulti-lateration system or a radar, sonar, or laser ranging system.Other examples of alternate technology RTLS tags include, but are notlimited to, systems employing inertial tracking, magnetic compasses,stereo vision tracking, or other such techniques.

In prior art (see for instance Horwitz U.S. Pat. No. 6,496,806), an IDtag reader has been employed to read tags associated with assets, read amultitude of similar tags associated with locations, and then correlatelocations with assets. Thus Horowitz must employ a vast multitude ofdistinct identification tags to achieve the same benefit as applicant'ssingle RTLS tag associated with a mover. Further, the characteristicsthat make a good identification technology (high reliabilityidentification at short range or line-of-sight) are not the same as thecharacteristics of a good location technology (high location at longrange or where line-of-sight may be restricted or blocked). Thus thepresent invention teaches that two distinct approaches should be merged,one optimized for identification, and one optimized for localization.

RTLS tags are typically larger in size than RFID tags and (whetherpassive or active) typically require electrical power from batteries oranother co-located power source. The system of the present inventionapplies the advantages of tow cost and small size of the ID tag to eachasset (where low cost and small size are most needed) and incorporatesthe advantages of the RTLS by placing the positioning system on themover where the cost of the positioning system can be applied to avirtually countless number of assets by repeated usages. Thus, thebenefits and shortcomings of the identification and localization devicesare complementary—each device overcomes the shortcomings of the otherdevice, enabling a system that would not be practical with either singledevice type alone.

Asset Identification, Localization, And Movement Process

FIG. 1 is an exemplary process flow diagram showing an assetidentification, localization, and movement process in accordance withthe present invention. The steps of FIG. 1 may be performed in anyorder, as desired. Of significance with respect to the steps of FIG. 1is that the localization equipment is installed on or otherwiseassociated with the mover, as is the ID tag reader. A low cost ID tag isattached or otherwise associated with the asset. Referring to FIG. 1,the process may begin with asset identification 10 a and may alsooptionally include asset localization 9 a. Typically, a worker isinstructed to move an asset to a new location within a warehouse. Theworker first finds the asset by going to the last known location of theasset 9 a and looking for the asset according to an asset identification10 a (typically a barcode number or RFID). When the asset is found, andidentified 10 a, the asset is picked up and moved 11 to the newlocation. The new location may not be precisely identified until theworker arrives at the area and finds an empty spot. Upon placing theasset at the new location, the asset location is measured 9 b preciselyand recorded in a database. The asset identification may then beoptionally verified 10 b. In an alternative sequence, the asset may beidentified 10 b at the time of final placement and localization 9 b.(Localization means measuring the location of the asset in coordinatesmeaningful to the facility.) Other sequences of localization andidentification may be desirable for other scenarios. Thus, thelocalization and identification is accomplished without installingexpensive active trackers on each asset. A particularly novel andinnovative feature of Applicants' invention is that the association ofthe RTLS tag with the ID tagged asset is a temporary one that existsonly for the duration of the process. That this combination is transientand temporary is both non-obvious and provides Applicants' approach withbenefits hitherto unrealizable by the prior art.

FIG. 2 is an exemplary schematic diagram describing one embodiment asystem for identification, localization, and movement of an asset. Theembodiment of FIG. 2 comprises a worker 18, a forklift 20, an activeRTLS tag 24 co-located with worker 18, a localizing ID reader (LIDR) 25,one or more locator receivers 19, a computer 23, and an ID tag 26co-located. with an asset 21. The worker 18 with or without the vehicle(e.g. forklift 20) acts as a movement agent capable of moving asset 21between locations. The LIDR 25 is a device with both active locationcapability and ID tag reading capability housed in the same unit, thuseliminating issues relating to associating the ID tag reader with thelocation tag.

An active RTLS tag 24 co-located with worker 18 works in conjunctionwith locator receiver 19 and computer 23 to localize worker 18 and thusassociated asset 21. A LIDR 25 co-located with forklift 20, inconjunction with a locator receiver 19 and computer 23, may also servefor localizing forklift 20 and associated asset 21. The LIDR 25 and IDtag 26 co-located with asset 21 cooperate to serve as identifying meansfor asset 21. Whereas, FIG. 2 illustrates the possible use of both anactive RTLS tag associated with the worker and a LIDR associated withthe forklift, only one locator is necessary.

As shown in FIG. 2, the LIDR is mounted on the body of the forkliftwhere the LIDR can sense tags on assets loaded at the lower position ofthe lift. Alternatively, the LIDR may be located on the lift to belifted up with the asset and positioned forward next to the asset tobetter represent the actual position of the asset.

In operation, the active RTLS tag 24 (associated with a movement agent,such as a worker 18) transmits a signal to one or more locator receivers19, as necessary to determine a location measurement. A computer 23accepts data from at least one locator receiver 19 and determines thelocation of active RTLS tag 24 and, thus, the movement agent, such as aworker 18. If asset localization process 9 a and/or 9 b is performed inconjunction with asset identification process 10 a and/or 10 b, thenassociated asset 21 becomes both localized and identified. By performingasset localization process 9 a and 9 b before and after asset movementprocess 11, an accurate location for asset 21 may be maintained incomputer 23.

In alternative embodiments, asset identification process 10 may beperformed by an active RTLS tag 24 associated with the asset 21 (ratherthan the mover) transmitting a signal to a locator receiver 19. Thesignal may be modulated so as to uniquely identify asset 21.Alternatively, a generic signal may be transmitted at a unique frequencyor at a unique time so as to uniquely identify asset 21. A datainterface 54 to active RTLS tag 24 may allow active RTLS tag 24 torespond on command from computer 23 so as to uniquely identify asset 21.

In a preferred embodiment, however, asset identification process 10 maybe performed by an ID tag reader 28 associated in location with amovement agent, such as worker 18. Physical association of the ID tagreader with the movement agent may be by being carried by the worker orby being mounted on a forklift operated by the worker or other similararrangement. Logical association of the active RTLS tag information withthe ID tag reader information may be made possible by a data exchange orhandshaking between ID tag reader 28 and active RTLS tag 24, as eachdevice will have a serial number identifying the device. In alternateembodiments, ID tag reader 28 may convey data to computer 23intermediate active RTLS tag 24, i.e., by sending data through activeRTLS tag 28, thus providing associated location and identification datafor asset 21. In further embodiments, ID tag reader 28 may provideidentification data directly to computer 23 in conjunction with adequateidentifying information pertinent to active RTLS tag 24 to enablecomputer 23 to associate a measured location of active RTLS tag 24 withidentification information relevant to asset 21. For example, eachdevice may separately communicate with the computer over the network,but the two devices may be defined or configured in software as beingfixed to the same forklift.

In still further alternate embodiments, association may follow fromco-locating functionality of ID tag reader 28 and active RTLS tag 24 ina localizing ID reader, LIDR 25. The LIDR 25 is a single unit withactive RTLS tag and ID tag reading capability. A worker 18 withco-located active RTLS tag 24 and transportation vehicle such as aforklift 20 with co-located LIDR 25 may similarly be associated by adata exchange or handshaking between active RTLS tag 24 and LIDR 25, theresults of said data exchange or handshaking being conveyed to computer23.

ID tag reader 28 reads an ID tag 26 associated with asset 21. ID tag 26may be a bar code, an RFID tag, an optical pattern tag, an alternatetechnology tag, or some combination of ID tag modalities. Onecombination of particular value is a bar code or optical patterncombined with an RFID tag.

The asset identification, localization, and movement process continueswith asset movement process 11. Asset movement process 11 comprises amovement agent acting so as to transport asset 21. Typical movementagents include, but are not limited to, a worker 18 either solo or inconjunction a transporter such as a hand truck, forklift 20, palletjack, crane, reach truck, side loader, order picker, or other materialhandler or lifter. Further benefits and features of the assetidentification, localization, and movement process may be betterunderstood with reference to an illustrative logistics process.

An Illustrative Logistics Process

FIG. 3 is a process flow diagram showing an illustrative logisticsprocess encompassing the asset identification, localization, andmovement process of FIG. 1. Each movement line indicated between two ofthe blocks may be performed in accordance with the identification,localization and movement process of the present invention. Theillustrative logistics process is not intended to be a comprehensive oruniversally applicable description of all logistics processes. Rather,the illustrative logistics process of FIG. 3 is intended to illustratethe potential benefits of the asset identification, localization, andmovement process in a logistics process.

The illustrative logistics process begins with start block 1 andproceeds with asset acceptance and receiving process 2 in which an assetin receiving, like asset 21, is received and accepted. A critical aspectof asset acceptance and receiving process 2 is a determination of wherean asset in receiving should go next. If an asset in receiving has beenmistakenly shipped, if paperwork accompanying an asset in receiving isflawed, or if some other significant problem is identified with an assetin receiving, then the illustrative logistics process may continue witha quarantine process 3. If an asset in receiving is to be stored forsufficient time to justify placing an asset in receiving into inventory,then the illustrative logistics process continues with asset ininventory process 4. If an asset in receiving is to be immediatelyreleased or shipped, then the illustrative logistics process maycontinue with a cross-dock transfer to an asset release and shippingprocess 7. If an asset in receiving comprises sub-assets that requirerepackaging, subdivision, or recombination, then the illustrativelogistics process may continue with asset break-out process 6.

The illustrative logistics process further comprises a quarantineprocess 3. In a quarantine process 3, an asset in quarantine (like asset21) is placed in secure storage because of some problem identified inpaperwork, a mis-shipment, or other problem necessitating secure storageof an asset in quarantine. If the problem is satisfactorily resolved,the illustrative logistics process may continue with asset in inventoryprocess 4. Alternatively, if an asset in quarantine comprises sub-assetsthat require repackaging, subdivision, or recombination, then theillustrative logistics process may continue with asset break-out process6. Finally if an asset in quarantine is to be released, shipped, orreturned to the point of origin, then the illustrative logistics processmay continue with a cross-dock transfer to an asset release and shippingprocess 7.

The illustrative logistics process further comprises an asset ininventory process 4. An asset in inventory process 4 involves an asset(like asset 21) being stored, for instance, in a pallet rack (likepallet rack 66), or in a staging or other storage area. If an asset ininventory has been mistakenly shipped, if paperwork accompanying anasset in inventory is flawed, or if some other significant problem isidentified with an asset in inventory, then the illustrative logisticsprocess may continue with a quarantine process 3. If an asset ininventory is to be released or shipped, then the illustrative logisticsprocess may continue with an asset release and shipping process 7. If anasset in inventory comprises sub-assets that require repackaging,subdivision, or recombination, then the illustrative logistics processmay continue with asset break-out process 6.

An asset in inventory may be subject to a periodic identification suchas in asset identification process 10. Further, an asset in inventorymay be subject to a periodic localization such as in asset localizationprocess 9. This realization enables an effective system and method forinventory control without necessarily requiring an asset to be moved.

The illustrative logistics process further comprises an asset break-outprocess 6. Asset break-out process 6 involves an asset in break-out(like asset 21) being divided into sub-assets and being repackaged,processed, sub-divided, and/or recombined so as to create new assets.For instance, an asset in break-out may be a pallet comprising sixparticular goods requiring repackaging to go to six differentdestinations. One asset in break out may be divided into multiple assetsin break-out, multiple assets in break-out may be combined into asmaller number of assets in break-out, or more complicated combinationsand divisions are possible.

If an asset in break-out is to be released or shipped, then theillustrative logistics process may continue with an asset release andshipping process 7. If an asset in break-out has been mistakenlyshipped, if paperwork accompanying an asset in break-out is flawed, orif some other significant problem is identified with an asset inbreak-out, then the illustrative logistics process may continue with aquarantine process 3. If an asset in break-out is to be stored forsufficient time to justify placing an asset in receiving into inventory,then the illustrative logistics process continues with asset ininventory process 4.

The illustrative logistics process further comprises asset release andshipping process 7. Asset release and shipping process 7 involves anasset in shipping being processed for release and shipment. If an assetin shipping is shipped, then the illustrative logistics processterminates in end block 8. If an asset in shipping has been mistakenlysubjected to asset release and shipping process 7, then the illustrativelogistics process may continue with a quarantine process 3 in which thefurther disposition of an asset in shipping may be decided.

An Illustrative Logistics Facility

FIG. 4 is a schematic diagram of an illustrative logistics facility 50.The illustrative logistics facility 50 is not intended to becomprehensive and universally applicable to all logistics facilities.Rather, the illustrative logistics facility of FIG. 4 is intended toillustrate the benefits of the asset identification, localization, andmovement process in a typical logistics facility, either stand-alone oras a department in a larger business or other enterprise.

The illustrative logistics facility 50 comprises an acceptance andreceiving area 12, inventory area 14, quarantine zone 13, break-out area16, and release and shipping area 17. The illustrative logisticsfacility 50 further includes assets (like asset 21), workers (likeworker 18), forklifts (like forklift 20), robotic forklifts (likerobotic forklift 105), hand trucks (like hand truck 15), locatorreceivers (like locator receiver 19), pallet racks (like pallet rack66), and a computer (like computer 23).

In receiving area 12, forklift 20 picks up asset 21 from truck 22. ALIDR 25 co-located with forklift 20 relays location and identificationinformation via locator receiver 19 to computer 23. Computer 23 may senddata to LIDR 25 to instruct worker 18 where to transport asset 21. Whenforklift 20 drops off asset 21 at a destination, a LIDR 25 co-locatedwith forklift 20 relays location information via locator receiver 19 tocomputer 23. In alternate embodiments, a LIDR 25 co-located withforklift 20 may further relay identification information via locatorreceiver 19 to computer 23 as a double-check or confirmation of theoriginal identification when forklift 20 drops off asset 21.

In asset break-out area 16, a worker 18 is leaving with an asset 21conveyed by a hand truck 15. Worker 18 identifies asset 21 by using IDtag reader 28. Active RTLS tag 24 co-located with worker 18 relayslocation information on worker 18 via locator receiver 19 to computer23.

Note that in accordance with the present invention, particularlyvaluable assets may warrant continuous monitoring and may haveassociated thereon a dedicated active RTLS tag 24, which may includeidentification information within the active RTLS tag. For example, inquarantine area 13, a particularly valuable asset 21 with a co-locatedactive RTLS tag 24 relays location information on worker 18 via locatorreceiver 19 to computer 23. Active RTLS tag 24 may include an on boardaccelerometer 53 to detect motion and alert computer 23 via locatorreceiver 19 if motion occurs. A worker 18 entering quarantine area 13may be tracked to maintain a security log of those having enteredquarantine area 13 or to ensure that only authorized workers (likeworker 18) have entered quarantine area 13.

An additional benefit of Applicant's system is that a robotic forklift(like robotic forklift 105), may additionally employ a real-timelocation system (RTLS) (like that enabled by active RTLS tag 24 and alocator receiver 19) in support of autonomous navigation and guidance.Further, determining the location of workers (like worker 18) enables acollision avoidance or proximity warning system, avoidingworker-forklift collisions.

Asset Identification, Localization, And Movement System Features

FIG. 5 is an exemplary schematic diagram describing forklifts placingassets at various levels in a rack. Asset location in the verticaldimension may require additional location determination resources. Inone embodiment, locator receivers 19 may be placed at the floor leveland an additional set may be placed at the ceiling level to providevertical received signal differences to resolve the vertical dimension.

In a further alternative, a set of locator receivers may be placed in aplane with sufficient numbers to triangulate in three dimensions.However, dilution of precision limits the ability of the tracking systemto determine elevation using location devices co-located in a commonhorizontal plane.

In a third alternative embodiment, elevation of an asset 21 in a palletrack 66 may be determined by sensing the forklift elevation with anelevation sensor. Typically, an elevation sensor may be coupled to themechanical lift 27 for the forklift 20. The elevation signal is thenconveyed to the computer 23 either directly via the network or throughthe active RTLS tag 24 or LIDR 25 associated with the forklift 20. Asshown in FIG. 5, three forklifts 20 a-20 c are unloading three assets 21a-21 c into three different heights in pallet rack 66. For eachdifferent height, the respective fork lifting mechanisms 27 a-27 c areextended to different lengths as may be measured by a sensor coupled tothe lift mechanism (sensor internal to mechanism 27 a-27 c).

In a further alternative, where the lift device has multiple dimensionsof lift and/or extension or travel, such as a crane, the extensiondimensions may be sensed and added to the location determined from thelocalizer receivers to determine the asset location. To add horizontalextension information, a direction must also be known.

In a further alternative, the active RTLS tag signal may be directional,indicating the horizontal orientation (azimuth) of the active RTLS tagby using radio direction techniques. In one embodiment the azimuth ofthe active RTLS tag is determined by a magnetic compass sensor. Inanother embodiment the azimuth is determined by radio direction signals.

In a further aspect, the location of the active RTLS tag that ismeasured when the asset is placed in the destination location may beoffset from the actual asset location. For example, if the active RTLStag is one meter back from the forks of the forklift, the positionmeasured is actually in the aisle in front of the asset. However, theoffset may be accommodated by noting that the forklift may be operatedto consistently measure asset position from directly in front of eachrespective asset. Thus, each asset may be paired one to one with acorresponding location such that the corresponding locations for eachasset are not ambiguous. Further, a forklift returning to a measuredlocation for a particular asset will be in position to load theidentified asset even though the asset may actually be extended from themeasured location.

FIG. 6A is a schematic diagram showing a first exemplary embodimentasset and personnel localizing system involving a worker 18 using an IDtag reader 28 to identify an asset 21. A first alternate embodimentsystem for identification, localization, and movement of an asset 21comprises a worker 18, an active RTLS tag 24 co-located with worker 18,an ID tag reader 28, a locator receiver 19, a computer 23, and an ID tag26 co-located with an asset 21.

An active RTLS tag 24 co-located with worker 18 works in conjunctionwith locator receiver 19 and computer 23 to serve as localizing means,localizing worker 18 and thus associated asset 21. AN ID tag reader 28and an ID tag 26 co-located with asset 21 cooperate to serve asidentifying means for asset 21.

FIG. 6B is a schematic diagram showing a second exemplary embodimentasset and personnel localizing system involving a healthcare worker 18using localizing ID reader (LIDR) 25 to identify and localize a varietyof assets 21 d-21 g. In this embodiment, LIDR 25 merges the capabilitiesof ID tag reader 28 and RTLS tag 24 c. LIDR 25 further may convey datato a computer or server 23, as well as support additional user interfacecapabilities for providing feedback to healthcare worker 18. In thisembodiment, RTLS tag 24 c is a passive RTLS tag, detecting signal 102and achieving localization in a manner described more fully inapplicant's “System and method for near-field electromagnetic ranging,”(Ser. No. 10/355,612 filed Jan. 31, 2003, now U.S. Pat. No. 6,963,301),applicant's co-pending “Method and apparatus for determining locationusing signals-of-opportunity,” (Ser. No. 12/796,643; filed Jun. 8,2010), and applicant's co-pending “Near-field electromagnetic locationsystem and method,” (Ser. No. 12/977,067; filed Dec. 23, 2010). Signal102 may be a signal-of-opportunity from an AM broadcast station 103 asshown, an alternate signal-of-opportunity, a beacon signal, or other RFor acoustic signal. A beacon signal may be a near-field signal or afar-field signal. All three of the applications noted above are hereinincorporated by reference. Note that passive RTLS tag 24 c provides adecentralized localization, calculating its own location without need ofany infrastructure (other than signals of opportunity 102). In alternateembodiments, however, RTLS tag 24 c may be an active RTLS tag, or analternate technology RTLS tag.

RTLS tag 24 c may employ compact and/or orthogonal antenna systems suchas those described in applicant's “Near field location system andmethod,” (Ser. No. 11/272,533; filed Nov. 10, 2005, now U.S. Pat. No.7,307,595), applicant's “Space efficient magnetic antenna system,” (Ser.No. 11/473,595; filed Jun. 22, 2006, now U.S. Pat. No. 7,755,552),applicant's co-pending “Space efficient magnetic antenna method,” (Ser.No, 12/834,821; filed Jul. 12, 2010), and applicant's co-pending “Planarantenna system,” (Ser. No. 12/857,528; filed Aug. 16, 2010). All fourapplications are herein incorporated by reference.

ID tag reader 28 reads and identifies ID tags 26 d-26 j associated withrespective assets 21 d-21 g. Patient 21 d wearing ID tag 26 d may beidentified and localized by LIDR 25. Medication 21 e with attached IDtag 26 e may be identified and localized by LIDR 25. Moveable equipmentor tools such as IV Pump 21 f with associated ID tag 26 f may beidentified and localized by LIDR 25. Fixed assets like hand-washing sink21 g with associated ID tag 26 g may be identified and localized by LIDR25. In each case, the identification and localization data obtained byLIDR 25 may be made available in a database on computer or server 23 anas to aid health care managers and analysts to confirm that the correcttreatments and services are provided to patient 21 d, and to quantifythat service in support of billing as well as visibility and improvementof the healthcare process. Data on server 23 may be made availableelsewhere via network 101. Network 101 may be protected from unwantedaccess using applicant's co-pending “Malicious attack response systemand method,” (Ser. No. 12/843,002; filed Jul. 23, 2010) which is hereinincorporated by reference.

In Applicants' invention, a relatively low number of active tags (as lowas one if only a single mover is employed) can be “reused” multipletimes in succession for tracking different passive tagged assets,drastically improving the economics of asset tracking in a logistics,warehouse, healthcare, or other environment. Thus Applicants' proposedcombination of low number of RTLS tagged carriers in temporaryassociation with a potentially large number of ID tagged assets yieldssynergies beyond what would be predicted by one of ordinary skill in theart.

Near-Field Location System

In a preferred embodiment, the RTLS tag and optional locating receiverof the present invention are based on transmitting and receiving nearfield signals. Location by near field signals is fully described in theUS patents and patent applications incorporated by reference above. Insummary, near field signals are signals received within a near field ofthe transmitter. The near field is best within ⅙ wavelength, but theeffects may be utilized out to one wavelength or so. Near field signalsshow unique amplitude and phase changes with distance from thetransmitter. In particular E field and H field antennas couple indifferent ways to the signal with different amplitude decay profiles anddifferent signal phase changes with distance. These amplitude and phaseprofiles may be used to measure distance. In particular, by comparing Efield and H field phase or E field and H field amplitude, distance maybe determined by referring to the theoretical predictions for themeasured property as a function of distance. Alternatively, the signalproperties may be pre-measured for a particular site to account for sitespecific disturbances and the range measurement compared with previouslymeasured data. An E field antenna is typically a whip antenna and may beon the order of a meter in length for a 1 MHz signal. An H field antennais typically a coil and may include a ferrite core. The H field antennamay be on the order of a few centimeters in length, width, and height.Thus, it can be advantageous to utilize magnetic antennas for mobileunits because of the compact size and to use both E field and H fieldantennas for the fixed units because of the size of the whip antenna. Insome situations however, the reverse may be desired. Numerous variationsare disclosed in the applications incorporated by reference above.

In particular, an often preferred configuration utilizes a magneticantenna (H field antenna) for the mobile beacon transmitter (active RTLStag) and a vertically polarized E field antenna with two orthogonallyoriented H field antennas for each of the fixed receiver locations. Thetwo H field antennas have the null axes in the horizontal plane. Anexemplary signal set from this arrangement includes:

E, Electric field strength from the E field antenna

H1, magnetic field strength from the first H field antenna

H2, magnetic field strength from the second field antenna

EH1, phase angle between E and H1 signals

EH2, phase angle between E and H2 signals

Thus, multiple determinations of range my be made from thisconfiguration by making different comparisons between E field and Hfield amplitude and phase. Typically, a weighted average of availabledeterminations is used based on the strongest or most reliable signalsfrom the set.

To find a position within an area, as needed for the exemplary warehouseexample, typically multiple receivers are positioned to allowtriangulation based on multiple range measurements, i.e., to eachlocation receiver from the active RTLS tag. If height is desired,additional receivers may be deployed to improve the height resolution.The receivers may be connected to a central computer for combining themeasurements from all receivers to determine location. The connectionmay be by wired or wireless network or other methods as desired.

In a further alternative embodiment, the area may be pre-measured toaccount for specific local propagation disturbances and to reduce errorsfrom equipment variations. A calibration set of measurements is made byplacing an active RTLS tag or a passive RTLS tag at known locations andmeasuring the signals and phases at all receivers. A finer grid, or setof grids, of locations may be generated from extrapolation andinterpolation from the measured locations. In operation, an unknownlocation is determined by transmitting from the unknown location andcomparing the set of measured data from all receivers with the storedcalibration data to find a location having the best match. Alternately,a passive RTLS tag may compare received signals with the storedcalibration data to find a location having the best match. Best matchmay be determined by summing absolute value of the differences betweeneach respective signal from each receiver, the best match being thelowest sum. In the sum, amplitudes and phases may be scaled to havesimilar effect on the sum. Weak signals may be ignored. Other criteriamay be applied to weight each element. Other matching criteria such assum of squared differences or other error criteria may be used. In oneembodiment, a location is determined as the centroid of a region havingan error value above a predetermined threshold. In further embodiments,motion constraints, such as walls and motion dynamics including momentumare used to improve position.

Locator-Receiver Functional Block Diagram

FIG. 7 is a functional block diagram showing an exemplary near fieldlocator receiver 19 for use in conjunction with an asset and personnellocation, identification, and movement system. In a preferredembodiment, locator receiver 19 comprises a first magnetic antenna 29,an electric antenna 31, a second magnetic antenna 30 (collectively,“three antennas”), and locator receiver board 43. Locator receiver board43 comprises first (pre-) amplifiers 32, and first mixers 34 that mix RFsignals from three antennas with a signal from first local oscillator 68to yield intermediate frequency (IF) signals. Band pass filters 35 andsecond amplifiers 36 convey IF signals to second mixers 37 that mix IFsignals with a signal from a second local oscillator to yield basebandsignals. Phase lock loops 38 stabilize response, increase stability, andreduce noise of baseband signals. A microprocessor 40 compares basebandsignals to timing signals from clock 41 to measure phase differencesbetween baseband signals. In one embodiment, the signals E, H1, H2, EH1,and EH2 as described above being E field and H field magnitudes andphases are measured by the receiver. Microprocessor 40 conveys resultsto computer 23 via data interface 42. Data interface 42 may be a wiredor wireless data network capable of transferring data betweenmicroprocessor 40 and computer 23.

FIG. 8 is a mechanical diagram showing a side view of a locator receiver19 for use in conjunction with an asset and personnel location,identification, and movement system. Locator receiver 19 comprises firstmagnetic antenna 29, electric antenna 31, second magnetic antenna 30,locator receiver board 43, and enclosure 44. First magnetic antenna 29and second magnetic antenna 30 are arranged so as to have mutuallyorthogonal nulls oriented in the plane of the floor of the warehouse.

FIG. 9 is a mechanical diagram showing a top view of a locator receiver19 for use in conjunction with an asset and personnel location,identification, and movement system. Locator receiver 19 comprises firstmagnetic antenna 29, electric antenna 31, second magnetic antenna 30,locator receiver board 43, and enclosure 44. First magnetic antenna 29and second magnetic antenna 30 are arranged so as to have mutuallyorthogonal nulls with null axes in the horizontal plane. FIG. 9 showsthe first magnetic antenna 29 and second magnetic antenna 30 asexemplary coils 29 and 30 respectively. FIG. 9 further illustrates theexemplary coils 29 and 30 wound on the enclosure 44 which is used as acoil form 44 for coils 29 and 30. Note the diagonal winding of the coils29 and 30 on the linear coil form 44. The diagonal winding is to rotatethe null axis 45 degrees relative to the axis of the form 44 so that thenull axes of the two coil null axes for coils 29 and 30 may beorthogonal, 90 degrees from one another.

Active RTLS Tag Functional Block Diagram

FIG. 10 is a functional block diagram showing an exemplary active RTLStag for use in conjunction with an asset and personnel location,identification, and movement system. Active RTLS tag 24 a comprises aclock or frequency reference 50, a microprocessor 45, a data interface54, a navigation sensor and/or other sensors 53, a first RF oscillator46, a second RF oscillator 47, a first RF amplifier 48, a second RFamplifier 49, a first (I) magnetic antenna (52), and a second (Q)magnetic antenna (51), and, if provided, a lift position sensor 55 for aforklift.

A data interface 54 provides for data to be conveyed to or received fromthe computer 23 or other devices on the network, such as an LIDR 25, anID tag reader 28, or another active RTLS tag 24 b. The data interface 54may be a wireless data network such as ZigBee®, WiFi®, or other networkor communication link. In alternate embodiments, data interface 54 maybe a receive-only simplex link and signals generated by a first (I)magnetic antenna 52 and a second (Q) magnetic antenna 51 may bemodulated to transmit data.

In a preferred embodiment, the first RF amplifier 48 and the second RFamplifier 49 have an input power of 50 mW so that active RTLS tag 24 isin compliance with FCC regulations Part 15.219. Also in a preferredembodiment, a first RF oscillator 46, and a second RF oscillator 47 arephase offset so as to yield a quadrature transmit signal withomni-directional properties, i.e., first magnetic antenna is driven 90degrees out of phase with respect to second magnetic antenna. Signalsgenerated by a first (I) magnetic antenna 52 and a second (Q) magneticantenna 51 cooperate to yield a near-field signal which may be detectedby one or more locator receivers 19 to determine the locationcoordinates of the active RTLS tag.

The active RTLS tag may also include an optional navigation sensor 53.The navigation sensor may include one or more of a magnetic compass,odometer, accelerometer, speedometer, gyro, turn sensor, or otherdevices that may assist the RF positioning system in determining aposition or orientation. Navigation may be used to filter noisy RFposition measurements, to dead reckon in locations with weak RFcoverage, or to provide additional dimensions of measurement, such asazimuth orientation of the forklift. In one embodiment, a motion sensor,such as an accelerometer, may be used to detect motion related tounauthorized movement of assets.

ID Tag Reader Functional Block Diagram

FIG. 11 is a functional block diagram showing an exemplary ID tag reader28 for use in conjunction with an asset and personnel location,identification, and movement system. ID tag reader 28 a comprises datainterface 56, microprocessor 57, transmitter 58, and receiver 59.

A data interface 56 provides for data to be conveyed to or received froma computer 23 or other devices on the network such as an LIDR 25,another ID tag reader 28 b, or an active RTLS tag 24. A data interface54 may be a wireless data network such as ZigBee®, or other network.

The ID tag reader also includes an operator switch to initiate an IDreading. The switch may also initiate a location reading from the activeRTLS tag. In one embodiment, upon receipt of an ID reading by thecomputer 23, the computer will initiate a location reading, from theactive RTLS tag that is associated with the ID reader as set up in thecomputer software.

Transmitter 58 excites ID tag 26 and receiver 59 receives identifyinginformation from ID tag 26. In a preferred embodiment, ID tag 26combines a bar code and an RFID device. ID tag reader 58 uses a laser toread the bar code of ID tag 26, and an RFID reader to receive data froman RFID chip embedded in ID tag 26. In alternate embodiments, opticalpattern or other technologies may be incorporated in ID tag 26.

ID tag readers typically have a short operational range, thus thepositioning of the mover together with the reading of the ID tagindicates the ID tag and associated asset are close to the location ofthe mover. By proper training of the worker to, for example, performlocation and identification operations with the forklift directly infront of and close to the asset, the measurements may be made moreaccurate and repeatable.

ID tag reader 28 a further includes user interface 67. User interface 67can convey such information to worker 18 as a destination, status, orother information pertinent to asset 21 in particular and the logisticsprocess in general.

Locating Identification Reader (LIDR)

FIG. 12 is a block diagram showing interfaces for an exemplary LIDR 25for use in conjunction with an asset and personnel location,identification, and movement system. The LIDR 25 combines thefunctionality of RTLS tag 24 and ID tag reader 28 in a single devicepackage. A LIDR 25 may include data interfaces for data to be conveyedto or received from a computer 23 or other devices on the network suchas another LIDR 25, an ID tag reader 28, or an active RTLS tag 24. ALIDR 25 radiates a signal capable of being localized by alocator-receiver 19, or embodies other passive RTLS or alternatetechnology RTLS capability. A LIDR 25 also can interrogate ID tag 26 soas to acquire identification data pertinent to asset 21.

The LIDR may be mounted on a moving vehicle such as a forklift, handtruck, pallet jack or other vehicle, or may be carried by a worker.Advantages of the LIDR include the fixed association of the active RTLStag and ID reader, the convenience of having both devices in onepackage, and the sharing of interface, battery and computer resources.

Alternate Embodiment Active RTLS Tag Mechanical Diagram

FIG. 13 is a mechanical diagram showing an alternate embodiment activeRTLS tag 68 for use in conjunction with an asset and personnel location,identification, and movement system, Alternate embodiment active RTLStag 68, battery 61, first magnetic antenna 51 comprising a plurality ofhollow core magnetic antennas 63, second (Q) magnetic antenna comprisingan orthogonal hollow core magnetic antenna 52, hanger 60, power cord 62,power jack 64 and power outlet cover holder 65.

Short magnetic antennas cylindrical cores with a small length todiameter ratio (L/D<˜10) tend not to have an effective permeability(μ_(e)) much greater than ten no matter what the effective bulkpermeability of the bulk core material (see for instance M. F. “Doug”DeMaw, Ferromagnetic Core Design & Application Handbook, Starkville,Miss.: MFJ Publishing Company, 1996, p. 41). The inventors havediscovered that if a core is relatively short (L/D<˜10) hollow cores(like those of hollow core magnetic antennas 63) yield performancecomparable to those of analogous solid cores. Hollow cores areadvantageous because of less material and therefore lower weight andless cost.

In preferred embodiments, hanger 60 is preferentially relatively stiffand allows alternate embodiment active RTLS tag 68 to be substantiallyrigidly mounted on a rear-view mirror of a vehicle or other placement.The relative stiffness of hanger 60 prevents alternate embodiment activeRTLS tag 68 from substantial swinging that might impair stability orperformance. Hanger 60 makes alternate embodiment active RTLS tag 68well-suited for use in conjunction with tracking rental or othervehicles or for tracking forklifts. Power cord 62 and jack 64 cooperateto allow alternate embodiment active RTLS tag 68 to be plugged into astandard 12V (“cigarette tighter”) car power jack or other power outlet.

Inventory Control System

FIG. 14 is a schematic diagram showing an inventory control system 104.In alternate embodiment inventory control system 104, stationary assets(for instance asset 21 h, asset 21 j, and asset 21 k) in an inventoryarea (such as that containing 66) remain stationary while a mover (likeforklift 20 d) traverses the inventory area employing LIDR 25 to read acollection of asset tags (for instance asset tag 26 l, asset tag 26 m,asset tag 26 n, asset tag 26 o, asset tag 26 p, and asset tag 26 q)associated with particular assets (asset 21 l, asset 21 m, asset 21 n,asset 21 o, asset 21 p, and asset 21 q, respectively). LIDR 25 canidentify multiple assets by interrogating or reading multiple asset tagssimultaneously, associate their identification with a particularlocation, and convey the appropriate data to server 23. This associationoccurs while a mover is in known relative proximity to an asset.However, a long ID tag read range necessarily introduces a certainambiguity in location. Certain ID tag read techniques (for instance,optical, laser, or IR) can read an ID tag, locate it in a field of view,and thus also comprise an alternate direction measuring deviceconfigured to measure the direction of an extension from a LIDR 25 so asto provide a more refined location. In an alternate embodiment multiplemore short range ID tag readers (like ID tag reader 28 h, ID tag reader28 i, ID tag reader 28 j, and ID tag reader 28 k) can be employed tosimultaneously read multiple ID tags (for instance asset tag 26 h, assettag 26 j, and asset tag 26 k) associated with particular assets (asset21 h, asset 21 j, and asset 21 k, respectively).

An automated inventory control system 104 subjects assets in inventoryto periodic identification and localization in support of a variety ofgoals. Inventory control system 104 is useful for providing adouble-check or confirmation that assets are present in the appropriatelocations, whether for audit, regulatory, contractual, financial, orother reasons.

An Inventory Control Method

FIG. 15 a is an exemplary process flow diagram showing an inventorycontrol method in accordance with the present invention. Of significancewith respect to the steps of FIG. 15 a is that the localizationequipment is installed on or otherwise associated with the mover, as isthe reader. A low cost ID tag is attached or otherwise associated withthe asset. Referring to FIG. 15 a, the process may begin in any orderwith asset identification 10 c and asset localization 9 c. Assetidentification 10 c is the step wherein an ID reader or ID tag readerinterrogates or otherwise detects ID tags associated with assets (assettags). Asset localization 9 c is the step wherein localizationequipment, such as an active wireless RTLS tag, passive RTLS tag, oralternate technology RTLS tag is employed in localization, determiningthe location of an associated mover. The mover may be a vehicle such asa forklift, a robot, a manually operated mover such as a hand truck orlift jack, or a person.

The determined location of the mover may then be associated with theappropriate asset and recorded as in asset location recording step 104.Asset location recording step 104 involves associating locationcoordinates (based on the determining location coordinates for the moverfrom asset localization step 9 c) with the asset (whose identity wasdetermined in asset identification step 10 c). This association occurswhile a mover is in known relative proximity to an asset. Asset locationrecording step 104 may further involve recording an asset location in adatabase on a server or a computer, or otherwise making asset locationdata available in service of other goals. The step of assetidentification 10 c and the step of asset localization 9 c may beperformed by a single organic device incorporating both functions, suchas a LIDR.

Note that in the sense of the inventory control process of FIG. 15 a,the mover does not move the asset. As a mover (for instance a forklift,robot, or person) traverses or moves around an inventory area, theinventory control process of FIG. 15 a is repeated multiple times, onefor each asset detected in an inventory area. The inventory controlprocess of FIG. 15 a greatly speeds and automates inventory controlparticularly compared to manual methods of verification.

FIG. 15 b is an alternate exemplary process flow diagram showing aninventory control method in accordance with the present invention. Theinventory control process of FIG. 15 b begins (in no particular order)with the parallel steps of associating an RTLS tag with a mover 9 d andassociating an ID tag with an asset 10 d. Then the inventory controlprocess of FIG. 15 b continues (in any order) with asset identification10 e and asset localization 9 e. The inventory control process of FIG.15 b makes explicit the step of associating an RTLS tag with a mover 9 dimplicit in the asset localization step 9 c. The inventory controlprocess of FIG. 15 b also makes explicit the step of associating an IDtag with an asset 10 d implicit in the asset identification step 10 c.

Other sequences of localization and identification may be desirable forother scenarios. Thus, the localization, identification, and acomprehensive, low-cost inventory control system may be accomplishedwithout installing expensive RTLS tags on each asset.

Conclusion

The present invention has been described above with the aid offunctional building blocks illustrating the performance of specifiedfunctions and relationships thereof. The boundaries of these functionalbuilding blocks have been arbitrarily defined herein for the convenienceof the description. Alternate boundaries can be defined so long as thespecified functions and relationships thereof are appropriatelyperformed. Any such alternate boundaries are thus within the scope andspirit of the claimed invention. One skilled in the art will recognizethat these functional building blocks can be implemented by discretecomponents, application specific integrated circuits, processorsexecuting appropriate software and the like or any combination thereof.

While various embodiments of the present invention have been describedabove, it should be understood that they have been presented by way ofexample only, and not limitation. One should understand that numerousvariations may be made by one skilled in the art based on the teachingsherein. Thus, the breadth and scope of the present invention should notbe limited by any of the above-described exemplary embodiments, butshould be defined only in accordance with the following claims and theirequivalents.

1. An inventory control method comprising: identifying an assetcomprising the steps of: associating an identification tag with theasset; and reading the identification tag with an IL) tag readerphysically associated with a mover, the mover having an RTLS tagthereon; logically associating the asset with the RTLS tag; determininglocation coordinates for the mover; logically disassociating the assetfrom the RTLS tag; recording location coordinates of the asset based onthe determining location coordinates for the mover.
 2. The inventorycontrol method of claim 1, wherein the RTLS tag is an active RTLS tag.3. The inventory control method of claim 1, wherein the RTLS tag is apassive RTLS tag.
 4. The inventory control method of claim 3, whereinthe passive RTLS tag employs signals-of-opportunity in determining alocation.
 5. The inventory control method of claim 1, wherein theidentification tag is an RFID tag.
 6. The inventory control method ofclaim 1 wherein the identification tag is an optical barcode label. 7.The inventory control method of claim 1, further including the step ofdetermining the location coordinates for said asset by measuredextension from the location coordinates for said mover.
 8. The inventorycontrol method as in claim 1, wherein said mover comprises a person. 9.The inventory control method as in claim 1, wherein said mover comprisesa robot.
 8. An inventory control system comprising: an RTLS tagassociated with a mover for determining location of the mover; an ID tagreader associated with the mover, the ID tag reader for determiningidentification of an asset from an ID tag associated with an asset; acomputer in communication with the RTLS tag and the ID tag reader forrecording a location of the asset, the computer configured forassociating the location of the mover with the identification of theasset.
 9. The inventory control system of claim 8: wherein the RTLS tagis an active RTLS tag for transmitting a location signal; and furthercomprising: a set of locator receivers for receiving the locationsignal; a computer in communication with the set of locator receivers,the computer configured for receiving measurements of the locationsignal made by the set of locator receivers, and the computerdetermining location coordinates of the active RTLS tag based on themeasurements of the location signal.
 10. The inventory control system ofclaim 8 wherein the RTLS tag is an active RTLS tag for transmitting alocation signal; and further comprising a set of locator receivers forreceiving the location signal and determining location coordinates ofthe active RTLS tag based on the measurements of the location signal;the set of locator receivers in communication with the computer, whereinthe computer is configured for receiving location coordinates of theactive RTLS tag from the set of locator receivers.
 11. The inventorycontrol system of claim 8, wherein the RTLS tag is a passive RTLS tag.12. The inventory control system of claim 11, wherein the passive RTLStag employs signals-of-opportunity in determining a location.
 13. Theinventory control system of claim 8, wherein the identification tag isan RFID tag.
 14. The inventory control system of claim 8 wherein theidentification tag is an optical barcode label.
 15. The inventorycontrol system of claim 8, further including the step of determining thelocation coordinates for said asset by measured extension from thelocation coordinates for said mover.
 16. The inventory control system asin claim 8, wherein said mover comprises a person.
 17. An inventorycontrol system comprising: an active RTLS tag for transmitting alocation signal; means for determining location coordinates for theactive RTLS tag based on the location signal; an ID tag reader incommunication with a computer, said ID tag reader for reading an assetidentification from an ID tag associated with an asset in an inventoryarea; a mover for carrying the ID tag reader and the active RTLS tag toa plurality of locations within the inventory area; wherein the locationcoordinates for the active RTLS tag are determined by the means fordetermining the location coordinates while the active RTLS tag is in aknown relative proximity to the asset; wherein the inventory controlsystem obtains an estimation of location coordinates for the asset fromthe location coordinates for the active RTLS tag, and wherein theinventory control system is configured for associating the locationcoordinates for the asset with the asset identification.
 18. Theinventory control system of claim 17 wherein the estimation furtherincludes the step of determining location coordinates for the asset bymeasured extension from the location coordinates for said mover.
 19. Theinventory control system as in claim 17, wherein the mover is a person.20. The inventory control system as in claim 17, wherein the mover is arobot.